The Internal Revenue Service (IRS) has taken the position it does not need a search warrant to gather email in criminal investigations, despite opposition from lawmakers and privacy advocates and a ruling by a federal appellate court.

Through the Freedom of Information Act, the American Civil Liberties Union (ACLU) obtained 247 pages of IRS records in an attempt to find out whether the agency had ever used only a subpoena to obtain emails. Unlike a warrant, a subpoena does not require law enforcement to show "probable cause" in front of a judge. Probable cause refers to having enough evidence to show that a crime has likely been committed.

Though inconclusive in what the ACLU was looking for, the records show that the IRS has taken the position at least since October 2011 that only a subpoena is needed to obtain emails more than 180 days old, as described in the 1986 Electronic Communications Privacy Act. That position was outlined in a memo written by William Spatz, a senior counsel of the IRS. It is also written in the agency's current manual of policies and procedures.

"Through their documents, [the IRS seems] to take the position that the Fourth Amendment has nothing to say about their access to people's emails," Nathan Wessler, a staff attorney for the ACLU in Washington, D.C., said on Thursday.

In a statement sent to CSO, a sister publication of Computerworld, the IRS said it does not use emails to target taxpayers, but the agency did not address the use of subpoenas. "Our job is to administer the nation's tax laws, and we do so in a way that follows the law and treats taxpayers with respect," the IRS said. "Contrary to some suggestions, the IRS does not use emails to target taxpayers. Any suggestion to the contrary is wrong."

If the IRS seeks emails without a warrant, then it is going against a rising tide of opposition. Opponents of warrantless email gathering include Internet companies such as Google, Microsoft, Yahoo and Facebook -- and some lawmakers.

In March, Senate Judiciary Committee Chairman Patrick Leahy, D-VT., and Sen. Mike Lee, R-Utah, introduced an amendment to the ECPA that would require a warrant for electronic communications stored with a third-party service provider.

The Justice Department has dropped its opposition to requiring warrants for emails in criminal cases, but wants to keep the option of using subpoenas in civil investigations. The ACLU opposes the exception.A'A

The courts are also moving in the direction favored by privacy advocates. In 2010, the Sixth Circuit Court of Appeals ruled that law enforcement needed a warrant in order to obtain emails from a service provider.

"We find that the government did violate [defendant Steven] Warshak's Fourth Amendment rights by compelling his Internet service provider to turn over the contents of his emails," the court said in U.S. vs. Warshak.

Despite the decision, IRS attorneys have pointed out the ruling only applies to states under the appellate court, not the whole nation, according to the ACLU papers. As a result, subpoenas are still sufficient outside the court's jurisdiction.

Law enforcement agencies will seek subpoenas when there is a "reasonable possibility" that information sought is relevant to an alleged crime. The standard is much lower than "probable cause" required in obtaining a warrant.

While subpoenas may be easier to obtain for police, they shouldn't be used to skirt the Fourth Amendment, privacy advocates say. "The Fourth Amendment has never been about accommodating law enforcement's whim or making investigations easy for them," Wessler said.